Cooling and Trapping

Juha Javanainen

K. Okada, M. Wada, Takashi Nakamura +3 more

A cryogenic linear ion trap was developed for the minimization of the loss of trapped Be+ ions. Buffer gas cooling as well as laser cooling for light element ions was tested in the cryogenic trap. The lifetime for the He-gas-cooled Be+ ions was longer than 15 min with a liquid-He-cooled trap, although they are known to be difficult to cool with a buffer gas in a conventional trap. A laser-cooled ion crystal was maintained for approximately 30 min without any ion loss.

Roman V. Krems, Břetislav Friedrich, William C. Stwalley

Andreas Wolfgang Schell, Oskar Sund

To control the motion of a trapped particle and prevent quantum state decoherence, cooling is required. In order to trap particles that do not offer cooling transitions, sympathetic cooling can be used. We are going to investigate the effects that arise from changing the trapping waveform applied to a Paul trap. We are especially interested in the comparison of the sympathetic cooling performance of the sinusoidal wave with its alternatives. We investigate different waveforms such as normal sine driven traps, but also traps driven with a saw-tooth, triangle, or square waveforms. From the simulation results, cooling rates as well as stability parameters are extracted. Ours findings indicate potential benefits of further in-depth studies on the key properties that trap driving waveforms should possess to enhance the sympathetic cooling efficiency in Paul traps.

Jamie Ryan Gardner

Vladilen S Letokhov

Abstract One of the most remarkable achievements of laser control is the manipulation of atomic particles, their velocities, positions, etc., which is referred to as laser cooling and laser trapping . These two effects are interrelated and usually prove effective when used jointly. That this is so one can see by considering as an example the laser cooling of trapped ions and the laser trapping of laser-cooled neutral atoms (Fig. 5.1). The sequences of processes in these two situations are directly opposite. Ions can easily be trapped in an electromagnetic trap of large depth (Paul 1990) and then be cooled for a long time by laser radiation (sideband cooling) (Wineland and Dehmelt 1975; Dehmelt 1990). Neutral atoms are first slowed down and cooled by laser radiation down to millikelvin temperatures, and only then confined in an optical trap. Trapped atoms can further be cooled to microkelvin temperatures. The present chapter and Chapter 6 consider the cooling and trapping of neutral atoms, the present chapter concentrating on their cooling, and Chapter 6 on trapping. But it would be reasonable first to familiarize the reader with the history of the early ideas in this field that eventually led to the advent of a new domain of physics—the physics of ultracold atoms and molecules (Chapters 7 and 8).